Method for sealing leaks in vessels

ABSTRACT

The invention relates to a method for sealing leaks in pipes, conduits, gaslines, closed containers, tanks and the like. The interior of such equipment is first purged with a nonreactive dry gas, such as nitrogen, to remove any moisture and/or oxygen which may be present. Then the sealing composition is introduced into the interior of the equipment in a suitable inert gas vehicle under pressure. The sealant composition in the gas vehicle will escape from any leaks present in the equipment into the outer ambient atmosphere or adjacent soil in the case of pipelines buried in soil. The sealant reacts with oxygen and/or moisture to form at the situs of the leak a solid reaction product. The sealant composition comprises (1) a volatile metal alkyl compound and (2) a volatile organosilane compound. The volatile metal alkyl compound has the formula M(R)2, wherein M is zinc or cadmium, or the formula X(R)3, wherein X is aluminum, gallium, indium, or thallium, and R is an alkyl having 1 to 3 carbon atoms. The organosilane compound has the formula R4 nSi(OR&#39;&#39;)n, wherein R is an alkyl having 1 to 3 carbons atoms, R&#39;&#39; is an alkyl having 1 to 3 carbon atoms, and n is an integer from 1 to 4. The proportions of the metal alkyl compound may range by volume from about 1 percent to about 99 percent, the remainder being the organosilane compound. An illustrative sealant composition is a mixture by volume of 80 percent tetraethoxysilane and 20 percent diethyl zinc which is introduced in a stream of nitrogen into a pipeline under pressure to seal existing leaks. The sealant compositions are supplied to the interior of the apparatus or vessel which may contain leaks in sufficient concentration and suitable pressure so that upon escape from the leaks a solid seal will form in sites.

United States Patent 72] Inventor Amos R. Anderson Adrian, Mich. [21] Appl. No. 851,734 [22] Filed Aug. 20, 1969 [45] Patented Sept. 21, 1971 [7 3] Assignee Joseph J. Packo [54] METHOD FOR SEALING LEAKS IN VESSELS 13 Claims, No Drawings [52] U.S. Cl 264/36, 117/106 A, 264/85 [51] Int. Cl ..B29c 23/00, B290 27/17 [50] Field of Search 264/36, 85; 1 17/ 107.2

[56] References Cited UNITED STATES PATENTS 2,990,295 6/1961 Breining et al 1l7/106 D 3,114,970 12/1963 Whitacre l17/l07.2 3,198,167 8/1965 Bakish et al.. 1l7/107.2 3,508,962 4/1970 Manasevit et al 117/227 Primary ExaminerRobert F. White Assistant Examiner-Gene Auville Attorney-Joseph Rossman ABSTRACT: The invention relates to a method for sealing leaks in pipes, conduits, gaslines, closed containers, tanks and the like, The interior of such equipment is first purged with a nonreactive dry gas, such as nitrogen, to remove any moisture and/or oxygen which may be present. Then the sealing composition is introduced into the interior of the equipment in a suitable inert gas vehicle under pressure. The sealant composition in the gas vehicle will escape from any leaks present in the equipment into the outer ambient atmosphere or adjacent soil in the case of pipelines buried in soil. The sealant reacts with oxygen and/or moisture to form at the situs of the leak a solid reaction product. The sealant composition comprises (1) a volatile metal alkyl compound and (2) a volatile organosilane compound. The volatile metal alkyl compound has the formula M(R) wherein M is zinc or cadmium, or the formula X(R) wherein X is aluminum, gallium, indium, or thallium, and R is an alkyl having 1 to 3 carbon atoms. The organosilane compound has the formula R ,,,Si(OR wherein R is an alkyl having 1 to 3 carbons atoms, R is an alkyl having 1 to 3 carbon atoms, and n is an integer from 1 to 4. The proportions of the metal alkyl compound may range by volume from about 1 percent to about 99 percent, the remainder being the organosilane compound.

An illustrative sealant composition is a mixture by volume of 80 percent tetraethoxysilane and 20 percent diethyl zinc which is introduced in a stream of nitrogen into a pipeline under pressure to seal existing leaks. The sealant compositions are supplied to the interior of the apparatus or vessel which may contain leaks in sufficient concentration and suitable pressure so that upon escape from the leaks a solid seal will form in sites.

METHOD FOR SEALING LEAKS IN VESSELS FIELD OF THE INVENTION This invention relates to sealing leaks in pipes, conduits, closed containers, tanks, and closed systems adapted to contain fluids therein, hereinafter referred to generally as vessel." The invention is particularly adapted for sealing leaks in buried underground piping systems used for conveying fuel gas and also for sealing leaks in telephone and electrical conduits containing nitrogen or other inert gas under pressure.

SUMMARY OF THE INVENTION According to this invention the interior of the vessel is first purged with a dry nonreactive gas, such as nitrogen, to remove moisture and/or oxygen present. The sealant composition is then introduced into the interior of the vessel under pressure in gaseous fonn or in a suitable inert gaseous vehicle. When the sealant composition escapes through any existing leak in the vessel it reacts with oxygen and moisture present at the interior locus of the vessel where the leak exists and forms a solid product in situ which seals the leak. The sealant compositions consist essentially of l) a volatile metal alkyl compound and (2) a volatile organosilane compound. These sealant compositions are introduced in the vessel in a nonreactive vehicle gas, such as hydrogen, helium or nitrogen in amount so that upon escape of the admixed gas from a leak into the atmosphere a seal will be produced. These sealant agents are substances which are easily volatilized and which can be admixed with the inert vehicle gas and carried along with the gas in the vessel.

The volatile metal alkyls suitable for the present invention have the formula: MRR', wherein M is zinc or cadmium, R and R is a straight or branched chain alkyl having 1 to 3 carbon atoms, R and R being identical or different. Specific examples are dimethyl zinc, diethyl zinc, methyl ethyl zinc, methyl propyl zinc, diisopropyl zinc and dipropyl zinc. Corresponding alkyl cadmium compounds such as dimethyl cadmium, etc., may also be used.

Other suitable volatile metal alkyls which can also be used have the formula: X(R) wherein X is aluminum, indium, gallium or thallium and R is a straight or branched chain alkyl having 1 to 3 carbon atoms, the alkyls being identical or different. Examples of such compounds are trimethyl aluminum, triethyl aluminum, methyl diethyl aluminum, dimethyl ethyl aluminum, tripropyl aluminum, triisopropyl aluminum, and methyl diisopropyl aluminum and similar alkyls of gallium, indium or thallium.

The aforementioned volatile metal alkyls may be used singly or in mixtures thereof.

The volatile organosilanes have the formula: R ,,Si(OR'),, wherein R and R is a straight or branched chain alkyl having 1 to 3 carbon atoms, all the alkyls being identical or different, and n is an integer from 1 to 4. Specific examples are trimethyl ethoxy silane, dimethyl diethoxy silane, propyl trimethoxy silane, diisopropoxy dimethoxy silane. These volatile silanes may be used singly or in mixtures thereof with the volatile metal alkyls previously described.

The proportions of the volatile metal alkyls and volatile organosilanes may be varied over a wide range depending upon the partial vapor pressures of the specific volatilized components. In general, the proportions of the metal alkyl compound may range from about 1 percent to about 99 percent by volume, the remainder being the organosilane compound. It is preferred to keep the metal alkyl concentration below 30 percent by volume in the sealant composition, although higher concentrations may be used, keeping in mind that such higher concentrations may result in pyrophoric compositions which are difficult to handle. Furthermore, inasmuch as the organosilanes are generally less volatile than metal alkyls, a

greater quantity of the organosilanes will result in a more even 1 distribution in the vessel or pipeline of the components of the sures. The sealant compositions are not simple mixtures of the organometallic compounds but in many cases undergo complex interchange reactions which may be generalized as follows:

AlR;,+Si(OR) =R,Al0R+RSi(OR) ZnR,+RSi(OR) =RZnOR+R,Si(OR) When such products as well as any of the original components escape from a leak they will react with oxygen or moisture present at the situs of the leak to form complex solid reaction products that seal the leak. Also in the case of vessels or pipelines buried in the soil the escaping sealant compositions will react with the oxygen or moisture present in the soil at the situs of the leak and form a solid seal while at the same time the soil adjacent the solid seal will provide a matrix or reinforcement for the seal.

As stated previously the concentration of the two volatile sealant components used and the pressure of the vehicle gas used may be varied over a wide range depending upon the specific components used, the nature and size of the leaks which are to be sealed and the environmental conditions of the particular vessel and the like. The time of flow of the sealant composition can also be greatly varied accordingly in order to seal existing leaks.

If desired, the sealant compositions may be supplied to the user in containers or cylinders mixed in the proportions required for specific sealing operations. The compositions may be introduced into the vessel and the like by suitable means in controlled or metered amounts in the vessel which has been previously flushed and dried with an inert gas. The inert gas and the added sealant composition are maintained at a suitable pressure for a sufficient period of time to seal any leak present. Also if desired, the user may be supplied with a suitable container having under pressure an inert gas and the selected sealant agents mixed therein in suitable proportions which can be introduced directly into the vessel and the like. Also if desired, the specific components of the sealant composition can be introduced in volatilized condition separately in controlled amounts in the vessel and the like in which the inert gas is present under suitable pressure.

ILLUSTRATIVE EMBODIMENTS OF THE INVENTION EXAMPLE 1 A steel pipe section (7 feet long, three-fourth inch diameter) was drilled with an A inch hole to simulate a leak. The test pipe was buried under 30 inches of clay loam soil of 6.3 percent moisture content. One end of the pipe was connected to a valve-controlled feed line connected to a source of dry nitrogen gas for purging the pipe of any moisture or oxygen, and also as an inert gas carrier for the sealant composition. The nitrogen line was also connected to a bubbler vessel containing the liquid sealant composition. Pressure and flow indicators and monitors were also connected in the feed line. The other end of the test pipe was connected to a valved outlet line connected to a pressure gage and pressure recorder. The test pipe was first purged with a stream of dry nitrogen gas to remove oxygen and moisture. A liquid mixture of 20 percent diethyl zinc and percent tetraethoxy silane, by volume, was placed in a bubbler and nitrogen gas passed through the solution, at ambient temperatures, at a pressure of l p.s.i.g. The nitrogen gas, carrying the volatilized diethyl zinc and tetraethoxy silane vapors was passed into the test pipe until a seal was obtained. An effective seal was made after a 68 hour period in which the initial flow rate was 50 C.F.l-l. at 10 p.s.i.g. Pressure was kept constant and flow rate decreased as sealing took place. A final test to determine the effectiveness of the seal was made by increasing the nitrogen pressure on the system to l00 lbs. p.s.i.g. for a period of 24 hours. No leakage was indicated via the fiowmeter.

dimethyl diethoxy silane, by volume, was placed in the apparatus described above in Example 1 and nitrogen gas passed through the solution for a period of 192 hours. The moisture content of the soil was 6.2 percent. At the end of this period a seal was obtained which, upon testing, showed no leakage at lOO lbs. p.s.i.g. over a 24 hour period as indicated via the flowmeter.

EXAMPLE 3 A mixture of 20 percent diethyl zinc and 80 percent npropyl trimethoxy silane, by volume, was placed in the apparatus described in Example 1 and nitrogen gas passed through the solution for a period of 216 hours. The moisture content of the soil was 6.2 percent. At the end of this period a seal was obtained which, upon testing at 100 lbs. p.s.i.g., gave no indication ofleakage of the flowmeter.

EXAMPLE 4 A mixture of 20 percent diethyl zinc and 80 percent diisopropoxy dimethoxy silane, by volume, was placed in the apparatus described in Example I and nitrogen gas passed through the solution for a period of 190 hours. The moisture content of the soil was 3.6 percent. At the end of this time a seal was obtained which, upon testing at 100 lbs. p.s.i.g. for 24 hours, gave no indication of leak via the flowmeter.

EXAMPLE 5 A mixture of percent triethyl aluminum and 80 percent tetraethoxy silane, by volume, was placed in the apparatus described in Example 1 and nitrogen gas passed through the solution for a period of 168 hours. The moisture content ofthe soil was 6.0 percent. At the end of this period a seal was obtained which, upon testing at 6 lbs. p.s.i.g. for 24 hours, gave no indication ofleak via the flowmeter.

EXAMPLE 6 A mixture of 20 percent triethyl aluminum and 80 percent dimethyl diethoxy silane, by volume, was placed in the apparatus described in Example 1 and nitrogen gas passed through the solution for a period of 190 hours. The moisture content of the soil was 6.2 percent. At the end of this period a seal was obtained, which, upon testing at 60 lbs. p.s.i.g. for 24 hours, gave no indication of leak via the flowmeter.

EXAMPLE 7 A mixture of 20 percent triethyl aluminum and 80 percent n-propyl trimethoxy silane, by volume, was placed in the apparatus described in Example 1 and nitrogen gas passed through the solution for a period of 210 hours. The moisture content of the soil was 6.2 percent. At the end of this period a seal was obtained which, upon testing at 60 percent lbs. p.s.i.g. for 24 hours, gave no indication of leak via the flowmeter.

EXAMPLE 8 A mixture of 20 percent diethyl zinc and 80 percent trimethyl ethoxy silane, by volume, was placed in the apparatus described in Example 1 and nitrogen gas passed through the solution for a period of 190 hours. The moisture content of the soil was 6.2 percent. At the end of this time a seal was obtained which, upon testing at 100 lbs. p.s.ig. for 24 hours, gave no indication ofleak via the flowmeter.

EXAMPLE 9 A mixture of 5 percent diethyl zinc and 95 percent tetraethoxy silane, by volume, was placed in a bubbler and nitrogen gas passed through the solution, at ambient temperatures, at a pressure of 1 p.s.i.g. The nitrogen gas carrier which contains diethyl zinc and tetraethoxy silane vapors was passed into a pipe which was buried beneath the surface of the ground. A simulated leak consisted of a A; inches drilled hole. The soil was a clay loam, testing 6.3 percent moisture.

The vapors of the above sealant composition was passed into the pipe until a seal was obtained. An effective seal was made after a 214 hour period in which the initial flow rate was 50 C.F.H. at 10 p.s.i.g. Pressure was kept constant and flow rate decreased as sealing took place. A final test to determine the effectiveness of the seal was made by increasing the nitrogen pressure on the system to lbs. p.s.i.g. for a period of 24 hours. No leakage was indicated via the flowmeter.

ADVANTAGES The present invention is particularly suitable for sealing leaks caused by corrosion in pipelines buried in the soil as well as in the joints. in cases where bell and spigot joints for example are packed with caulked jute or other fibrous materials they tend too dry out and cause leaks especially when the pipelines are used to convey natural fuel gas which is extremely dry. Fuel gaslines buried underground in cities are also subjected to earth heaving and vibration caused by vehicles and trucks of the street traffic which produce leaks at the joints. The repair of such leaks is very costly because sections of the gas main must be exposed by excavating the superposed soil to gain access to the leaking joints for rescaling them. According to the present invention excavations are entirely eliminated. The section of the pipeline in which a leak exists is first dried internally by passing a stream of dry gas such as nitrogen. The sealant composition is then fed in a suitable gas vehicle through this section of the pipeline for a sufficient time until the leak is sealed. The sealant compositions of the present invention upon escape from leaks in such underground pipelines react with moisture and oxygen present at the situs of the leak to form a solid complex reaction product and at the same time the adjacent soil provides a reinforcing matrix for the seal. Such seals are impervious to fuel gas and are strong enough to withstand high pressures.

1 claim:

1. The method of sealing leaks in a vessel and the like adapted for containing a fluid therein which comprises the steps of introducing into the interior of said vessel a sealant composition comprising a volatilizable metal alkyl compound and a volatilizable organosilane compound, applying pressure on the interior of said vessel sufficient to permit escape of said sealant composition from a leak present in said vessel into the ambient environment and for a period of time sufficient to form a solid seal in the situs of the leak,

2. The method of claim 1 in which said sealant composition is introduced in admixture with a vehicle gas inert thereto.

3. The method of claim 11 in which the interior of said vessel is first purged to remove air and moisture therefrom.

4. The method of claim 3 in which the purge is performed by displacement by an inert gas.

5. The method of sealing leaks in a vessel as defined in claim 1 wherein the l volatilizable metal alkyl is selected from the group consisting of a volatilizable metal alkyl having the formula: MRR, wherein M is zinc or cadmium, and R and R is a straight or branched chain alkyl having 1 to 3 carbon atoms, the alkyls being identical or different; and a volatile metal alkyl having the formula: X(R) wherein X is aluminum, gallium, indium or thallium and R is a straight or branched chain alkyl having 1 to 3 carbon atoms, the alkyls being identical or different; and (2) the volatile organosilane compound has the formula: R wherein R and R is a straight or branched chain alkyl having 1 to 3 carbon atoms, the alkyls R' being identical or different, and n is an integer l to 4.

6. The method of sealing leaks in a vessel as defined in claim 1 wherein the sealant composition comprises diethyl zinc and tetraethoxy silane.

7. The method of sealing leaks in a vessel as defined in claim 1 wherein the sealant composition comprises diethyl zinc and dimethyl diethoxy silane.

8. The method of sealing leaks in a vessel as defined in claim 1 wherein the sealant composition comprises diethyl zinc and n-propyl trimethoxy silane.

aluminum and tetraethoxy silane.

12. The method of sealing leaks in a vessel as defined in claim 1 wherein the sealant composition comprises triethyl aluminum and dimethyl diethoxy silane.

13. The method of sealing leaks in a vessel as defined in claim 1 wherein the sealant composition comprises triethyl aluminum and ti n-propyl trimethoxy silane. 

2. The method of claim 1 in which said sealant composition is introduced in admixture with a vehicle gas inert thereto.
 3. The method of claim 1 in which the interior of said vessel is first purged to remove air and moisture therefrom.
 4. The method of claim 3 in which the purge is performed by displacement by an inert gas.
 5. The method of sealing leaks in a vessel as defined in claim 1 wherein the (1) volatilizable metal alkyl is selected from the group consisting of a volatilizable metal alkyl having the formula: MRR'', wherein M is zinc or cadmium, and R and R'' is a straight or branched chain alkyl having 1 to 3 carbon atoms, the alkyls being identical or different; and a volatile metal alkyl having the formula: X(R)3, wherein X is aluminum, gallium, indium or thallium and R is a straight or branched chain alkyl having 1 to 3 carbon atoms, the alkyls being identical or different; and (2) the volatile organosilane compound has the formula: R4 nSi(OR'')n, wherein R and R'' is a straight or branched chain alkyl having 1 to 3 carbon atoms, the alkyls R'' being identical or different, and n is an integer 1 to
 4. 6. The method of sealing leaks in a vessel as defined in claim 1 wherein the sealant composition comprises diethyl zinc and tetraethoxy silane.
 7. The method of sealing leaks in a vessel as defined in claim 1 wherein the sealant composition comprises diethyl zinc and dimethyl diethoxy silane.
 8. The method of sealing leaks in a vessel as defined in claim 1 wherein the sealant composition comprises diethyl zinc and n-propyl trimethoxy silane.
 9. The method of sealing leaks in a vessel as defined in claim 1 wherein the sealant composition comprises diethyl zinc and diisopropoxy dimethoxy silane.
 10. The method of sealing leaks in a vessel as defined in claim 1 wherein the sealant composition comprises diethyl zinc and trimethyl ethoxy silane.
 11. The method of sealing leaks in a vessel as defined in claim 1 wherein the sealant composition comprises triethyl aluminum and tetraethoxy silane.
 12. The method of sealing leaks in a vessel as defined in claim 1 wherein the sealant composition comprises triethyl aluminum and dimethyl diethoxy silane.
 13. The method of sealing leaks in a vessel as defined in claim 1 wherein the sealant composition comprises triethyl aluminum and ti n-propyl trimethoxy silane. 